Bird flu hits Northwest Iowa dairies7 this month

Avian influenza struck seven dairy farms in Iowa this month.

The Iowa Department of Agriculture and Land Stewardship on Monday reported that a dairy herd in Sioux County contracted the disease. Iowa Capital Dispatch reported it was a herd of over 10,000 head, one of the largest in the state. Five of the infected herds are in Sioux County; the other two are in Plymouth and O’Brien counties.

The U.S. Department of Agriculture has attributed most of the spread from Texas, where it was first identified this spring. Infected cows from there have been transported to other states. It is likely spread to dairies via human interaction and equipment transported between sites.

The USDA said in a press release last week that the disease has likely been transmitted by veterinarians, workers who operate at multiple farms and workers who live with people who work at other farms. The USDA also said that it hasn’t found evidence of wild birds introducing the infection in states beyond Texas.

The disease was expected to reach cattle in Iowa and other Midwestern states when it was first detected. Cattle have frequent interaction with wild birds. No evidence of such transmission has been found, according to the USDA. The virus has been identified in more than 100 herds in 12 states.

In addition to the spate of dairy herd infections in Northwest Iowa, a flock of 4.2 million egg-laying chickens in Sioux County was also culled. A turkey flock in Cherokee County was also culled earlier this month. Dairy herds aren’t culled like poultry flocks. Affected cows recover within two weeks after a temporary loss of production. Pasteurization of milk kills the virus.